Recent light-microscopic work in this laboratory has demonstrated color-specific features of interconnections between cones and horizontal cells in goldfish retina. We discovered three types of horizontal cell (HC) whose dendrites contact only cones: H1, which contact blue- green- and red-sensitive cones; H2, which contacts blue- and green-sensitive cones; and H3, which contacts only blue-sensitive cones. To explain the known functional properties of cone HC's, we proposed a model in which HC dendrites ar mainly postsynaptic to some cones (or HC's) but mainly presynaptic to others: R cone yields H1 (yields G cone) yields H2 (yields B cone) yields H3. Currently we are analyzing synapses between identified cones and horizontal cells by electron microscopy of serial ultrathin sections. We find that H3 dendrites are central in triads of ribbon synapses (i.e., probably postsynaptic) at certain B cones but lateral in triads (i.e., probably presynaptic) at other B cones; that H2 dendrites are central in triads of G cones but lateral in tirads of B cones; and the H1 dendrites are central in triads of r cones but lateral in triads of G and B cones. These findings are consistent with the model proposed earlier. Further studies will employ electrophysiological methods to examine functional properties of these interconnections, and light and electron microscopy to further elucidate cone-cone and cone-bipolar cell pathways.